The present invention relates to a crosslinkable polyion complex having an ethylenic double bond at a terminal position in the repeating unit of the polymer, and a polyion complex film. Previously, in processes for producing polyion complexes, combinations of two organic compounds, such as a combination of sodium polyacrylate or sodium polystyrene-sulfonate with a polyvinylbenzyltrimethyl ammonium salt have been used. (Encyclopedia of Chemical Technology, 6, 117-132; 1968). Other polyion complexes which have been synthesized are prepared by reacting an anionic, partial substituent of polyvinyl alcohol with a polyvinyl pyridinium salt. However, the conventional polyion complexes have low durability and low strength, and films made of the conventional polyion complex have unsatisfactory strength.
A need therefore, continues to exist for a method of obtaining polyion complexes having improved strength, especially for polyion complexes which form films.